Researchers from the Peter Doherty Institute of Australia examined Enterococcus faecium bacteria, which is one of the leading causes of infections in hospitals. More specifically, they found a particular group of bacteria, known as vancomycin resistant enterococci (VRE), has mutated to prevent alcohol from killing it.

The research team tested 139 samples of E. faecium taken from patients before and after alcohol-based hand sanitisers were adopted in Australian hospitals, covering a period from 1997 to 2015.

The samples were exposed to a disinfecting alcohol solution, which found that the bacteria collected after 2010 were ten times more tolerant to the substance.

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To investigate further, bacteria samples were applied to mice cages, which were cleaned up using hospital-strength sanitising wipes.

The results found that the mice placed in a cage with a 2012 strain of E. faecium excreted the bacteria, proving that the alcohol was not as effective compared to the earlier strains.

What’s more alarming is that the VRE group of bacteria is particularly dangerous to patients who have had a course of antibiotics, which disrupts the normal composition of their gut bacteria, thus, people who are the most sick in hospital are the most at risk. VRE bugs are already resistant to a string of antibiotics, and are known to cause infections in the urinary tract, wounds, and the bloodstream.

While the results are alarming, the researchers say it doesn’t mean it’s time to ditch the hand sanitiser; instead it’s time for a re-evaluation.

“This isn’t the end of hospital hand hygiene, that’s been one of the most effective infection control procedures that we’ve introduced worldwide,” said one of the study’s researchers and molecular biologist, Tim Stinear.

Disinfectants have proven to be extremely effective, but the study suggests they need to be used in combination with other procedures, and should always be used correctly.

“But we can’t rely solely on alcohol-based disinfectants and for some bacteria, like VRE, we’re going to need additional procedures and policies in place. For hospital this will be super-cleaning regimens, which include disinfectants, maybe chlorine-based,” Stinear explained.

The researchers suggests that as well as washing hands for a full 20-30 seconds, sanitisers with a higher percentage of alcohol and more efficient patient isolation might also help.

“An extra level of infection control, that doesn’t just rely on alcohol-based disinfectants is required,” said Stinear.